/*
 * Copyright (c) 2022 Institute of Software, Chinese Academy of Sciences (ISCAS)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package xyz.eulix.space.util;

import java.io.UnsupportedEncodingException;

/**
 * @author: chenjiawei
 * date: 2021/7/8 17:02
 */
public class Base64Util {
    private static char[] base64EncodeChars = new char[]
            { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
                    'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
                    'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5',
                    '6', '7', '8', '9', '+', '/' };
    private static byte[] base64DecodeChars = new byte[]
            { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53,
                    54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
                    12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29,
                    30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1,
                    -1, -1, -1 };

    private Base64Util() {
        throw new AssertionError("not allow to be instantiation!");
    }

//    public static String encode(byte[] data)
//    {
//        StringBuffer sb = new StringBuffer();
//        int len = data.length;
//        int i = 0;
//        int b1, b2, b3;
//        while (i < len)
//        {
//            b1 = data[i++] & 0xff;
//            if (i == len)
//            {
//                sb.append(base64EncodeChars[b1 >>> 2]);
//                sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
//                sb.append("==");
//                break;
//            }
//            b2 = data[i++] & 0xff;
//            if (i == len)
//            {
//                sb.append(base64EncodeChars[b1 >>> 2]);
//                sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
//                sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
//                sb.append("=");
//                break;
//            }
//            b3 = data[i++] & 0xff;
//            sb.append(base64EncodeChars[b1 >>> 2]);
//            sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
//            sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
//            sb.append(base64EncodeChars[b3 & 0x3f]);
//        }
//        return sb.toString();
//    }
//
//    public static byte[] decode(String str)
//    {
//        try
//        {
//            return decodePrivate(str);
//        } catch (UnsupportedEncodingException e)
//        {
//            e.printStackTrace();
//        }
//        return new byte[]
//                {};
//    }
//
//    private static byte[] decodePrivate(String str) throws UnsupportedEncodingException
//    {
//        StringBuffer sb = new StringBuffer();
//        byte[] data = null;
//        data = str.getBytes("US-ASCII");
//        int len = data.length;
//        int i = 0;
//        int b1, b2, b3, b4;
//        while (i < len)
//        {
//
//            do
//            {
//                b1 = base64DecodeChars[data[i++]];
//            } while (i < len && b1 == -1);
//            if (b1 == -1)
//                break;
//
//            do
//            {
//                b2 = base64DecodeChars[data[i++]];
//            } while (i < len && b2 == -1);
//            if (b2 == -1)
//                break;
//            sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
//
//            do
//            {
//                b3 = data[i++];
//                if (b3 == 61)
//                    return sb.toString().getBytes("iso8859-1");
//                b3 = base64DecodeChars[b3];
//            } while (i < len && b3 == -1);
//            if (b3 == -1)
//                break;
//            sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
//
//            do
//            {
//                b4 = data[i++];
//                if (b4 == 61)
//                    return sb.toString().getBytes("iso8859-1");
//                b4 = base64DecodeChars[b4];
//            } while (i < len && b4 == -1);
//            if (b4 == -1)
//                break;
//            sb.append((char) (((b3 & 0x03) << 6) | b4));
//        }
//        return sb.toString().getBytes("iso8859-1");
//    }
}
